1. Technical Field
This invention relates to a method and apparatus for mounting a brake disc in a disc brake. A particular application of the invention is to a spot-type automotive disc brake in which at least one, and preferably two brake discs are mounted for axial movement in use with respect to a central drive hub which drives the discs and on which they exert a braking effect during use. Typically, the central drive hub is a wheel mounting of an automobile. Certain aspects of the invention may find application outside the confines of spot-type automotive disc brakes.
2. Related Art
We have established that spot-type single or multi-disc disc brakes of the kind comprising axially movable discs can provide significant advantages over conventional spot-type automotive disc brakes. These advantages are set out in a series of patent applications which we have filed covering various aspects of the constructional differences between such brakes and conventional automotive disc brakes.
One aspect of these constructional differences relates to the use of resilient means acting between the one or more brake discs and the rotatable mounting therefor, such resilient means being provided to control certain aspects of the dynamics or movement of the brake discs during use. Reference is made to the disclosure in WO 98/26192 for a representative prior disclosure in this regard, and likewise too WO 98/25804. This latter disclosure concerns a disc brake system in which a plurality of leaf springs mounted on a hub and engaging the brake disc apply radially-directed forces between the disc and the hub.
However, we have discovered that the mode of mounting the resilient means with respect to the drive hub is of significance in relation to the effective operation of the resilient means for the brake as a whole, not to mention the resilient function itself.
As a matter of simple design principles, it is to be expected that the optimum arrangement would be as disclosed in our above-identified prior applications in which the resilient means is mounted on the hub and exerts its resilient or biasing effect on the disc by virtue of limited contact with the disc at certain well defined locations depending on the exact resilient means (or spring) design and the spring location.
Such an approach is consistent with the design principles emerging from the basic structure of the disc brake in which the relatively massive central hub provides a convenient reference base not only structurally for the mounting of the biasing springs, but also a relatively massive heat sink whereby a substantial thermal gradient exists in use between the brake disc with its locally-generated thermal energy and relatively low thermal capacity, whereby thermal factors favor minimizing the numbers of components to be subjected to frequent substantial thermal gradients, particularly components such as springs which are reliant upon thermally sensitive physical properties such as resilience.